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The axial mode oscillations are examined for relativistic rotating stars with uniform angular velocity. Using the slow rotation formalism and the Cowling approximation, we have derived the equations governing the r-mode oscillations up to…

Astrophysics · Physics 2015-06-24 Yasufumi Kojima , Masayasu Hosonuma

Perturbations of rotating relativistic stars can be classified by their behavior under parity. For axial perturbations (r-modes), initial data with negative canonical energy is found with angular dependence $e^{im\phi}$ for all values of…

General Relativity and Quantum Cosmology · Physics 2009-10-30 John L. Friedman , Sharon M. Morsink

A brief review of the stability of rotating relativistic stars is followed by a more detailed discussion of recent work on an instability of r-modes, modes of rotating stars that have axial parity in the slow-rotation limit. These modes may…

General Relativity and Quantum Cosmology · Physics 2008-11-26 John L. Friedman , Keith H. Lockitch

We present an analytic description of the $r$-mode instability in newly-born neutron stars, using the approximation of uniform density. Our computation is consistently accurate to second order in the angular velocity of the star. We obtain…

Astrophysics · Physics 2011-05-23 K. D. Kokkotas , N. Stergioulas

Quasi-toroidal oscillations in slowly rotating stars are examined in the framework of general relativity. The oscillation frequency to first order of the rotation rate is not a single value even for uniform rotation unlike the Newtonian…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Yasufumi Kojima

Several recent surprises appear dramatically to have improved the likelihood that the spin of rapidly rotating, newly formed neutron stars (and, possibly, of old stars spun up by accretion) is limited by a nonaxisymmetric instability driven…

General Relativity and Quantum Cosmology · Physics 2017-08-23 John L. Friedman , Keith H. Lockitch

The oscillation modes of stars play an important role in observations, and on the understanding of stellar stability properties. The role of viscosity in the oscillation modes of compact stars has been so far understood very loosely only,…

General Relativity and Quantum Cosmology · Physics 2026-04-16 Sofía Bussières , Jaime Redondo-Yuste , José Javier Ortega Gómez , Vitor Cardoso

The first numerical study of axial (toroidal) pulsation modes of a slowly rotating relativistic star is presented. The calculation includes terms of first order in $\epsilon \equiv \Omega \sqrt{R^3/M}<<1$ ($R$ is the radius, $M$ is the mass…

General Relativity and Quantum Cosmology · Physics 2009-07-09 Nils Andersson

The first results of numerical analysis of classical r-modes of {\it rapidly} rotating compressible stellar models are reported. The full set of linear perturbation equations of rotating stars in Newtonian gravity are numerically solved…

Astrophysics · Physics 2009-10-31 Shin'ichirou Yoshida , Shigeyuki Karino , Shijun Yoshida , Yoshiharu Eriguchi

In part I, we use the post-Newtonian (pn) order of Liouville's equation to study the normal modes of oscillation of a spherically symmetric relativistic system. Perturbations that are neutral in Newtonian approximation develop into a new…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Vahid Rezania

Stellar pulsations in rotating relativistic stars are reviewed. Slow rotation approximation is applied to solving the Einstein equations. The rotational effects on the non-axisymmetric oscillations are explicitly shown in the polar and…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Yasufumi Kojima

We derive the relativistic equations for stellar perturbations, including in a consistent way shear viscosity in the stress-energy tensor, and we numerically integrate our equations in the case of large viscosity. We consider the slow…

General Relativity and Quantum Cosmology · Physics 2010-11-11 L. Gualtieri , J. A. Pons , J. A. Miralles , V. Ferrari

We investigate properties of $r$-mode instability in slowly rotating relativistic polytropes. Inside the star slow rotation and low frequency formalism that was mainly developed by Kojima is employed to study axial oscillations restored by…

General Relativity and Quantum Cosmology · Physics 2010-11-19 Shijun Yoshida , Toshifumi Futamase

We study the r-modes and rotational ``hybrid'' modes of relativistic stars. As in Newtonian gravity, the spectrum of low-frequency rotational modes is highly sensitive to the stellar equation of state. If the star and its perturbations obey…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Keith H. Lockitch , Nils Andersson , John L. Friedman

Rossby waves (r-modes) in rapidly rotating neutron stars are unstable because of the emission of gravitational radiation. We study saturation of this instability by nonlinear transfer of energy to stellar "inertial" oscillation modes. We…

In this review we summarize the current understanding of the gravitational-wave driven instability associated with the so-called r-modes in rotating neutron stars. We discuss the nature of the r-modes, the detailed mechanics of the…

General Relativity and Quantum Cosmology · Physics 2014-11-17 N. Andersson , K. D. Kokkotas

Non-axisymmetric oscillations of rapidly rotating relativistic stars are studied using the Cowling approximation. The oscillation spectra have been estimated by Fourier transforming the evolution equations describing the perturbations. This…

General Relativity and Quantum Cosmology · Physics 2009-09-29 Erich Gaertig , Kostas D. Kokkotas

Techniques are developed here for evaluating the r-modes of rotating neutron stars through second order in the angular velocity of the star. Second-order corrections to the frequencies and eigenfunctions for these modes are evaluated for…

General Relativity and Quantum Cosmology · Physics 2016-08-25 Lee Lindblom , Gregory Mendell , Benjamin J. Owen

We use time-evolutions of the linear perturbation equations to study the oscillations of rapidly rotating neutrons stars. Our models account for the buoyancy due to composition gradients and we study, for the first time, the nature of the…

Astrophysics · Physics 2009-11-13 A. Passamonti , B. Haskell , N. Andersson , D. I. Jones , I. Hawke

In this work we study the r-mode instability windows and the gravitational wave signatures of neutron stars in the slow rotation approximation using the equation of state obtained from the density dependent M3Y effective interaction. We…

Nuclear Theory · Physics 2018-06-20 Somnath Mukhopadhyay , Joydev Lahiri , Debasis Atta , Kouser Imam , D. N. Basu
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